From: Linus Torvalds <torvalds@osdl.org>
To: Andrew Morton <akpm@osdl.org>
Cc: vrajesh@umich.edu, linux-kernel@vger.kernel.org, Linux-MM@kvack.org
Subject: Re: [PATCH] mremap NULL pointer dereference fix
Date: Mon, 16 Feb 2004 22:06:48 -0800 (PST) [thread overview]
Message-ID: <Pine.LNX.4.58.0402162203230.2154@home.osdl.org> (raw)
In-Reply-To: <20040216220031.16a2c0c7.akpm@osdl.org>
On Mon, 16 Feb 2004, Andrew Morton wrote:
>
> This saves a goto. It works, but I wasn't able to trigger
> the oops without it either.
To trigger the bug you have to have _just_ the right memory usage, I
suspect. You literally have to have the destination page directory
allocation unmap the _exact_ source page (which has to be clean) for the
bug to hit.
So I suspect the oops only triggers on the machine that the trigger
program was written for.
Your version of the patch saves a goto in the source, but results in an
extra goto in the generated assembly unless the compiler is clever enough
to notice the double test for NULL.
Never mind, that's a micro-optimization, and your version is cleaner.
Let's go with it if Rajesh can verify that it fixes the problem for him.
Rajesh?
Linus
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next prev parent reply other threads:[~2004-02-17 6:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-17 4:41 Rajesh Venkatasubramanian
2004-02-17 5:31 ` Andrew Morton
2004-02-17 5:38 ` Linus Torvalds
2004-02-17 5:49 ` Linus Torvalds
2004-02-17 6:00 ` Andrew Morton
2004-02-17 6:06 ` Linus Torvalds [this message]
2004-02-17 13:23 ` Rajesh Venkatasubramanian
2004-02-17 21:33 ` Rajesh Venkatasubramanian
2004-02-19 14:29 ` [PATCH] orphaned ptes -- mremap vs. truncate race Rajesh Venkatasubramanian
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